1. Field of the Invention
This invention relates to a method for detecting crystal defects in semiconductor silicon and also to a detecting solution therefor.
2. Description of the Prior Art
The use of detecting solutions which are mixtures of chromic anhydride and hydrofluoric acid for detecting crystal defects in semiconductor silicon is known. One of these solutions has been adopted as a detecting solution in the Japanese Industrial Standards. However, the known detecting solutions have a drawback in that their use and disposal may cause occupational diseases and environmental pollution because they contain a large amount of hexavalent chromium.
More particularly, the use of a mixed acid consisting of one part by volume of hydrofluoric acid (50%) and one part by volume of a solution obtained by dissolving 50 g of chromic anhydride in 100 cc of water to detect crystal defects in semi-conductor silicons which are broadly used as material in present-day electronics industry is known. Since the mixed acid includes a great amount of hexavalent chromium, a mist emerges in the course of etching and results in a dispersal of chromic acid in the air to pollute the working atmosphere. Thus, such use can cause an occupational disease due to the hexavalent chromium. In addition, the waste liquor from the processing has a high content of hexavalent chromium and presents environmental pollution problems to land and water.